Golf club heads come in many different forms and makes, such as wood- or metal-type (including drivers and fairway woods), iron-type (including wedge-type club heads), utility- or specialty-type, and putter-type. Each of these styles has a prescribed function and make-up. The present invention relates primarily to hollow golf club heads, such as wood-type and utility-type (generally referred to herein as wood-type golf clubs).
Wood-type or metal-type golf club heads generally include a front or striking face, a crown, a sole and an arcuate skirt including a heel, a toe and a back. The crown and skirt are sometimes referred to as a shell. The front face interfaces with and strikes the golf ball. A plurality of grooves, sometimes referred to as “score lines,” may be provided on the face to assist in imparting spin to the ball and for decorative purposes. The crown is generally configured to have a particular look to the golfer and to provide structural rigidity for the striking face. The sole of the golf club is particularly important to the golf shot because it contacts and interacts with the ground during the swing.
The complexities of golf club design are well known. The specifications for each component of the club (i.e., the club head, shaft, grip, and subcomponents thereof) directly impact the performance of the club. Thus, by varying the design specifications, a golf club can be tailored to have specific performance characteristics.
The design and manufacture of wood-type club heads requires careful attention to club head construction. Among the many factors that must be considered are material selection, material treatment, structural integrity and overall geometrical design. Exemplary geometrical design considerations include loft, lie, face angle, horizontal face bulge, vertical face roll, face size, center of gravity, sole curvature, and overall head weight. The interior design of the club head may be tailored to achieve particular characteristics, such as by including hosel or shaft attachment means, perimeter weighting on the face or body of the club head, and fillers within hollow club heads. Club heads are typically formed from stainless steel, aluminum, or titanium and are cast, stamped, as by forming sheet metal with pressure, forged, or formed by a combination of any two or more of these processes.
The club heads may be formed from multiple pieces that are welded or otherwise joined together to form a hollow head, as is often the case of club heads designed with inserts, such as soleplates or crown plates. The multi-piece constructions facilitate access to the cavity formed within the club head, thereby permitting the attachment of various other components to the head such as internal weights and the club shaft. The cavity may remain empty, or may be partially or completely filled, such as with foam. An adhesive may be injected into the club head to provide the correct swing weight and to collect and retain any debris that may be in the club head. In addition, due to difficulties in manufacturing one-piece club heads to high dimensional tolerances, the use of multi-piece constructions allows the manufacture of a club head to a tight set of standards.
Players generally seek a metal wood driver and golf ball combination that delivers maximum distance and landing accuracy. The distance a ball travels after impact is dictated by the magnitude and direction of the ball's translational velocity and the ball's rotational velocity or spin. Environmental conditions, including atmospheric pressure, humidity, temperature, and wind speed, further influence the ball's flight. However, these environmental effects are beyond the control of the golf equipment manufacturer. Golf ball landing accuracy is driven by a number of factors as well. Some of these factors are attributed to club head design, such as center of gravity, moment of inertia and club face flexibility.
Known methods to enhance the weight distribution of wood-type club heads to help reduce the club from being open upon contact with the ball usually include the addition of weights to the club body. These weight elements are usually placed at specific locations, which will have a positive influence, such as increasing moment of inertia or lowering center of gravity, on the flight of the ball or to overcome a particular golfer's shortcomings.
In addition to seeking to optimize the mass characteristics of club heads, players—most often highly skilled amateurs and tour professionals—may choose to customize the lie and loft angles of their clubs. See e.g., U.S. Pat. Nos. 6,260,250; 6,186,903 and 6,483,101. To achieve a more precise fit, the geometrical design of the club is altered by bending the hosel, thereby changing the orientation the of the club head at address position and at impact position. The known methods, however, often fail to produce predictable results due to inaccurate and inconsistent measuring of baseline loft and lie angles. As well, because most wood-type and hybrid clubs have rounded or curved soles, adjusting loft and lie angles unpredictably changes face angle; because the orientation of the club head at impact position has changed, the contact area between sole and ground at impact also changes and may force the club face open or closed, as opposed to square to the target, resulting in undesired hooking or slicing.
Hence, there remains a need for an accurate and repeatable system for hosel bending, and other methods of customizing the clubs for enhanced mass distribution.